1. The Field of the Invention
The present invention relates to extensible authentication and credential provisioning. More specifically, the present invention relates to automated negotiation of authentication mechanisms and limited-use credentials that can be used to provision additional credentials.
2. Background and Related Art
Computer systems and related technology affect many aspects of society. Indeed, the computer system's ability to process information has transformed the way we live and work. Computer systems now commonly perform a host of tasks (e.g., word processing, scheduling, and database management) that prior to the advent of the computer system were performed manually. More recently, computer systems have been coupled to one another to form computer networks over which the computer systems can communicate electronically to share data. As a result, many of the tasks performed at a computer system (e.g., accessing electronic mail and web browsing) include electronic communication with one or more other computer systems via a computer network (e.g., the Internet).
In order for one computer system to communicate electronically with another computer system, the computer system, as well as a corresponding computer system user, may need to authenticate with (i.e., prove its identity to) the other computer system (or a computer system that authorizes access to the other computer system. Depending on the environment, any of a wide variety of different computerized authentication mechanisms, such as, for example, Kerberos, Secure Sockets Layer (“SSL”), NT LAN Manager (“NTLM”), and/or Digest authentication, can be used.
Some authentication mechanisms include an interactive logon. For example, before a computer system can communicate electronically on the Internet, a user of the computer system is often required to log-in with an Internet Service Provider (hereinafter referred to as an “ISP”) that can authorize access to the Internet. Logging-in with an ISP typically includes a submission of user credentials (e.g., a username and a password) from the computer system to the ISP. Upon receiving the credentials, the ISP compares the credentials to a credentials database and if the credentials are appropriate the computer system is authorized to communicate with the Internet.
Unfortunately, there is always some risk of unauthorized users obtaining an authorized User's credentials and using the credentials to impersonate the authorized user. Since an authorized user's credentials essentially allow full access to all of authorized users resources on a particular system (e.g., files, electronic messages, personal and financial data, etc.), any compromise in credentials can provide an unauthorized user with the ability to copy and destroy the authorized user's resources. In particular, passwords are vulnerable to guessing attacks, for example, from programs that sequentially submit each word in a dictionary as a password (commonly referred to as “dictionary attacks”).
Other authentication mechanisms do not include an interactive logon and thus there are no user credentials that can be obtained. For example, a Web server can prove its identity to a Web client using SSL. When the Web client contacts a secured Web page at the Web server (e.g., a page beginning with “https:”), the Web server responds, automatically sending a digital certificate that authenticates the Web server. The Web client generates a unique session key to encrypt all communication with the Web server. The Web client encrypts the session with the Web server's public key (e.g., referenced in the certificate) so only the Web server can read the session key. Thus, a secure session is established without requiring any user actions.
Although examples of interactive authentication and non-interactive authentication mechanisms have been described, it should be understood that implementations of interactive authentication and non-interactive authentication can vary between networks and computer systems. For example, one network may be configured to use Kerberos authentication, while another network is configured to use some other interactive authentication mechanism. Further, a particular authentication mechanism can have different configuration options that cause the authentication mechanism to operate differently. For example, some implementations of SSL allow different encryption algorithms to be selected when establishing a secure session.
Unfortunately, it can be difficult or even impossible, to determine the authentication mechanism and/or configuration options a computer system or network has deployed. Thus, one computing system may attempt to authenticate with another computer system using an authentication mechanism and/or configuration option that is not deployed at the other computer system. As a result, authentication can fail and prevent the computing systems from communicating.
The potential for attempting to authenticate using an undeployed authentication mechanism is especially high in distributed systems. Distributed systems often include a number of interconnected computer systems and networks, where various portions of the distributed system are under the control of different entities. These different entities may each deploy different authentication mechanisms and may not necessarily advertise or publish an indication of the authentication mechanisms that are deployed. Thus, a first component of the distributed system may be prevented from authenticating with a second component of the distributed system because the first component does not know (and may have no way to determine) the authentication mechanisms deployed at the second component.
Other authentication problems can occur in wireless environments. For example, for a device to wirelessly authenticate with a mixed wired/wireless network, the device may be required to a have a certificate corresponding to the network. However, the network may be configured to allow only authenticated devices to access the certificate. Thus, the device may be required to initially connect to the network via a wired connection. Requiring a wired connection for access to a certificate can burden a user (e.g., a user may need to locate a network tap) and in some environments may be difficult (e.g., network taps may be in restricted access location) or even impossible (e.g., some devices are not configured for wired network access). Accordingly, even authorized users may be prevented from wirelessly accessing a network.
Therefore, what would be advantageous are mechanisms for automatically negotiating authentication methods and more securely provisioning of credentials.